The voting ends April 13th at 12.00 GMT.
It's hardly surprising that many of the nominees are made with AGS. They are by far the biggest community, and of the 109 games listed at TCN, 60 are made with AGS. But it does not mean that the TCN Awards are a second AGS award ceremony. There are several contenders made with other system.
And, what's more important, I don't think it matters one bit what engine was used to make a particular game. What matters is the end result. As you can see, there isn't a single mention of game engines on the award pages at TCN. (For the record, I'm a SLUDGE user myself.)